Dental calculus, or tartar as it is sometimes called, is a deposit which forms on the surfaces of the teeth at the gingival margin. Supragingival calculus appears principally in the areas near the orifices of the salivary ducts; e.g., on the lingual surfaces of the lower anterior teeth and on the buccal surfaces of the upper first and second molars, and on the distal surfaces of the posterior molars.
Mature calculus consists of an inorganic portion which is largely calcium phosphate arranged in a hydroxyapatite crystal lattice structure similar to bone, enamel and dentine. An organic portion is also present and consists of desquamated epithelial cells, leukocytes, salivary sediment, food debris and various types of microorganisms.
As the mature calculus develops, it becomes visibly white or yellowish in color unless stained or discolored by some extraneous agent. In addition to being unsightly and undesirable from an aesthetic standpoint, the mature calculus deposits are constant sources of irritation of the gingiva.
A wide variety of chemical and biological agents have been suggested in the art to retard calculus formation or to remove calculus after it is formed. Mechanical removal of this material periodically by the dentist is, of course, routine dental office procedure.
The chemical approach to calculus inhibition generally involves chelation of calcium ion and/or crystal growth inhibition which prevents the calculus from forming and/or breaks down mature calculus by removing calcium.
The prior art discloses a number of chelating agents for this purpose. British Pat. No. 490,384, Feb. 15, 1937, discloses oral compositions containing ethylenediaminetetraacetic acid, nitrilotriacetic acid and related compounds as anticalculus agents. This patent goes on to say: "other substances displaying a tartar dissolving action may be present in the tooth cleansing agent according to our present invention. As such additional ingredient we prefer the water soluble metaphosphates or pyrophosphates. In this connection there may be mentioned by way of example the alkali metal salts of these phosphates, especially sodium hexametaphosphate which may for instance be prepared by heating primary phosphates with subsequent rapid cooling of the melt. Also the water soluble salts of pyrophosphoric acids, for instance the secondary and quarternary alkali metal salts such as the sodium, potassium, lithium and ammonium salts and also the salts of certain basic organic compounds such as amines may be used." U.S. Pat. No. 3,678,154, July 18, 1972 to Widder et al discloses oral compositions containing certain polyphosphonates and fluoride. U.S. Pat. No. 3,737,533, June 5, 1973 to Francis discloses oral compositions containing certain carbonyl diphosphonates.
In addition to the above references, the prior art discloses dentifrices and mouthwashes containing soluble pyrophosphate salts which have been indicated for a variety of purposes. Include among such references are U.S. Pat. No. 2,941,926, June 21, 1960 to Salzmann et al which discloses dental powders containing chlorophyll and pyrophosphate salts. U.S. Pat. No. 3,137,632, June 16, 1964 to Schiraldi discloses toothpastes containing pyrophosphate salts. U.S. Pat. No. 3,927,201 and 202, Dec. 16, 1975 to Baines et al and Harvey et al, respectively, discloses toothpastes which utilize soluble pyrophosphates as abrasives. U.S. Pat. No. 4,244,931, Jan. 13, 1981 and 4,247,526, Jan. 27, 1981 to Jarvis et al disclose pyrophosphate salts in dicalcium phosphate systems. Jap. patent application Disclosure No. 4945-1974 discloses soluble pyrophosphates in a variety of dentifrice systems. U.S. Pat. No. 4,333,551, Apr. 6, 1982 to Parran discloses tetraalkali metal salts in mouthwash compositions. Finally Draus, Lesniewski and Miklos, Pyrophosphate and Hexametaphosphate Effects In Vitro Calculus Formation, Arch. Oral Biol., Vol. 15, pp. 893-896, (1970) disclose the in vitro effectiveness of soluble pyrophosphate salts against calculus. However, they indicate that pyrophosphate would be inhibited by pyrophosphatase in vivo.
The references suggesting that pyrophosphates could reduce calculus, but either suggesting problems associated with their use or not recognizing problems, are Rapp, G. W. et al., "Pyrophosphate: A Factor in Tooth Erosion", J. D. Res. March-April 1960, Vol. 39, No. 2 pp. 372-376; the Draus article cited above; Briner et al., "In Vitro and In Vivo Evaluation of Anticalculus Agents", Calc. Tiss. 11, pp. 10-22 (1973); U.S. Pat. No. 3,934,002, Jan. 20, 1976 to Haefele; and British Pat. No. 490,384, Feb. 15, 1937.
In spite of the many disclosures in the anticalculus and pyrophosphate areas, the need for an effective anticalculus product still exists. Surprisingly mixtures of certain pyrophosphate salts can provide a safe and effective product while also not presenting difficult formulation problems.
It is an object of the present invention to provide compositions which deliver an effective anticalculus benefit.
It is a further object of the present invention to provide an effective anticalculus product utilizing a mixture of soluble pyrophosphate salts.
It is still a further object of the present invention to provide an effective method for treating calculus.
These and other objects will become more clear from the detailed description which follows.
All percentages and ratios used herein are by weight unless otherwise specified.